Fluid-pressure-operated tool.



- P ,ATENTBD APR. 28, 1903.

- o. H. JOHNSON.

FLUID PREssUREgoPBRATED Toor..

APPLICATION FILEDv JAN. 25, 1902.

i .'L'lllllllllllllll` minimum nIlllllllll N ii 7f3-fined@ No MODEL.

Utri-3D STAT-nsl CHARLES I-I. JOHNSON, OF CHICAGO, ILLINOIS.

FLUID-Passenari-OPERATED TOO t.

,SPECIFICATION forming part of Letters Patent No. 726,305, dated April 28, 1 903..

4 Application tied tammy 25,1902. saranno. 91,203. (Numan.)

invented a certain new and useful Improve` ment in Fluid-Press'ure-Operated Tools; and

I declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it pertains to make and use the same, reference being had to the accompanying drawings, which form a part of this specification.

My invention relates in general to iiuidpressure-operated tools, and more particularly to the type ofsuch tools commonly known as pneumatic hammers.

In pneumatic toolsin whicha constant pressure is maintained upon the piston in the direction of the tool the throw of the piston away from the tool has heretofore been effected by first exposing the larger end of the piston to pressure from the motive-'fluid supply and then cutting oft' the supply and allowing the expansion of the pressure admitted to the cylinder to complete the throw-of the piston. It is obvious that in a tool so constructed the pressure to which the-piston is exposed during the latter part of its throw away from the tool is reduced bythe expansion of the fluidl within the cylinder.

The object of my inventionisto provide a fluid-pressure-operated'tool of the type referred to in which the speed of the piston during its movement away from the tool is not diminished after the motive-fluid supply is cut off, but is accelerated by exposing the piston to Huid-pressure admitted from a reservoir.

A further object of my invention is to provide a Huid-pressure-operated tool which will be simple in construction and efcient in operation.

Myinvention, generally stated, consistsiu a fiuid-pressure-operated tool comprising a cylinder, a piston exposed to a constant pressure in the direction of the tool, and a reservoir which is charged with pressure from the motive-duid supply andwhich discharges to accelerate the latter part of the movement of the piston away from the tool.

My invention will be more fully described hereinafter,wth reference to the accompanying drawings, in which the same is illustrated as embodied in a convenient and practical form, and in which- Figure 1 is a longitudinal section through a tool embodying my invention,` showing the piston delivering a blow upon the tool; Fig. 2, a view similar to Fig. l, showing the piston at the beginning ofits stroke toward the tool; Fig. 3, a fragmentary view showing a modification of my invention, and Figs. 4. and 5 sectional views on lines-i 4 and 5 5, Fig. l.

Similar reference characters are used to designate similar parts in the several figures of the drawings.

Reference-letter A designatesa cylinder one end of which is interiorly screw-threaded to be engaged by the screw-threaded extension Ct of the coupling A. A handle B is provided with an interiorly-screw-threadedtubular portion B,which engages the screw-th readed portion of the couplingA opposite'to that engaged by the end ofthe cylinder A. -Any suitable means may be provided for preventing the rotation of the handle with respect to the coupling A', such means being shown as consisting in a spring-actuated'bolt h2, which engages with ratchet-teeth formed on the eX- teriorfsurface of the endof the coupling A.

A ferrule E is fitted within'th'e end of the cylinder opposite to the end engaged by the coupling A. Asnap ordieor theshank of the tool F extends through thev ferrule E and is frictionally engaged therein by any suitable means-such, for instance, as a spring-ring e, seated within a groove in the ferrule E.

A bushing C is located Within the cylinder A and is retained therein against longitudinal displacement by means of a radially-projecting flange c', which is engaged by the end a of the coupling A. An exterior4 shoulder` is formed by an enlarged portion C4of the bushing, which engages a shoulder a4, formed on the interior surface of the cylinder A. The end of the bushing adjacent to the ferrule E is spaced within the cylinder A by means of an interposed ring C'. VThe end C2 of the bushing C adjacent to the annular flange c' has a reduced bore, which is retained concen- ICO trically Within the cylinder by means of an annular flange, through which are formed ports o3. The annular projecting portion C4 of the bushing C is provided with a series of i longitudinal passages c4 and a series of ports in register with a series of exhaust-ports a, formed through the cylinder A. The bore of the bushing between the projecting portion C4 and the reduced portion c2 is enlarged to form the chamber Cwhich tapers slightly at the point Where the exhaust-ports are located and continues to the spacing-ring C with a uniform diameter, forming the chamber C5. A series of ports c5 extend through the bushing C, connecting the chamber C5 with a space between the exterior of the bushing and the interior of the cylinder A. A small port c6 also extends through the bushing C at a point adjacent to the spacing-ring C'. Within the bushing C is located a piston D, comprising an extended portion of a diameter to correspond with the diameter of the chamber C2 of the bushing and two annular shoulders d and CZ', closely fitting within the chamber C5 of the bushing, but ofaslightlyless diameter than the diameter of the chamber C3 of the bushing.

Any desired form of throttle-valve may be employed for controlling the admission of pressure through the handle to the cylinder. Such throttle-valve for convenience is shown as consisting in a pop-valve B5, located within a chamber in the handle B' and normally seated by means of a spring b5.

B4 indicates a coupling, to which a pipe leading from the motive-Huid supply is secured.

B3 indicates the valve-stern, which is secured at one end to the throttle-Valve B5 and at its other end is engaged by a hand-operated lever B2, pivotally mounted in the handle B.

IJ indicates a passage in the handle B, leading from a chamber above the throttle-valve to the interior of the coupling A.

In Fig. 3 I have illustrated a modification in the means for permit-ting the fluid-pressure to How into the end of the cylinder adjacent to the shank of the tool'. Instead of providing a restricted port 06, as in Figs. l and 2, I have provided a longitudinal groove c7 upon the inner surface of the chamber C5 of the bushing, through which huid-pressure may pass from the chamber C5 to the end of the cylinder to be exerted upon the combined areas of the end of the piston and the vertical surface of the annular projection di The operation of my improved fluid-pressure-operated tool is as follows: A hand-lever B2 is depressed, as indicated in Fig. 2, which through the interposed spindle B3 unseats the throttlevalve B5. Motive Huid then iiows from the source thereof through the coupling B4, thence through the throttle-valve, and through the passage b to the interior of the coupling A. Vhen the piston is in the position indicated in Fig. 1,.the `fluid-pressure passes through the series of ports c2, through the bushing, thence through ports c3, formed in the annular flange between the bushing and the cylinder A, thence through the space between the chamber C3 of thebushing and the interior surface of the cylinder, through the longitudinal passages o4, formed through the annular projecting portion C4 of the bushing, thence into the space between the chamber C5 of the bushing and the interior surface of the cylinder, thence through the restricted ports c6 to the end of the cylinder. The end of the piston adjacent to the tool as well as the vertical face of the annular shoulder d are then exposed to pressure from the source thereof, and consequently the piston is moved toward the handle of the tool, overcoming the pressure exerted upon the opposite end of the piston, owing to the latter being of less area than the combined areas of the end and vertical face of the shoulder (l of the piston. l/Vhen the end of the piston adjacent to the handle covers the ports c2, through the bushing, and thereby cuts off further flow of pressure from the source thereof to the space between the exterior surface of the bushing and the interior surface of the cylinder, the annular projection CZ on the piston has passed the series of ports c5, so that the Huid-pressure which has been stored in the space constituting a reservoir between the bushing and cylinder expands against the end of the piston and the vertical face of the shoulder d, thereby accelerating the movement of the piston during the portion of its stroke away from the tool after the source of huid-supply has been out off. The piston continues its stroke away from the tool until the annular projection d thereon has passed the series of exhaust-ports a, whereupon the duid-pressure which has propelled the piston away from the tool escapes to the atmosphere and permits the lesser area of the opposite end of the piston, which is exposed to a constant pressure from the source of motive Huid, to move the piston toward the tool, the shank of which receives the impact of the piston. The interior diameter of the portion C3 of the bushing C is slightly greater than the combined diameter of the piston and the annular projections d or d. Consequently when the annular projections pass the exhaust-ports ct during the stroke of the piston toward the handle of the valve communication between the chamber C3 and exhaust-ports a, around the piston is permitted, thereby avoiding the compression of fluid between the annular projections and the shoulder formed between the portions C3 and C2 of the bushing.

The operation of the modification shown in Fig. 3 is similar to the operation of the embodiment shown in Figs. 1 and 2 except that a groove c7 is provided upon the interior surface of the endof the bushing adjacent to the shank of the tool through which fluid-pres- IOO IIO

IIS

sure passes to the end of the cylinder to impart the initial movement of the piston away from the tool. The groove c7 takes the place of the restricted port c6 in the specific form shown in Figs. l and 2.

From the foregoingdescription it will be observed that I have invented an improved iiuid-pressure-operated tool of the type in which the pistou is exposed to a constant pressure in the direction of the tool, the stroke of the piston of which away from the tool is accelerated after the su pply thereto of pressure lfrom the motive-iiuid source has been cut off by exposing the larger areaof the piston to pressure which has been stored in a reservoir.

While I have described more or less precisely the details ot' construction, I do not wish to be understood as limiting myself thereto, as I contemplate changes in form, the proportion of parts, and the substitution of equivalents, as circumstances may suggest or render expedient, without departing from the spirit of my invention.A

Having now fully described my invention, what I claim as new, and desire to secure by Letters Patent, is

l. In a fluid-pressure-operated tool, the

. combination with a cylinder, of a reciprocating piston therein exposed to a constant pressure toward the tool, means for admitting fluid-pressure from the motive-fluid source to impart an initial movement to the piston away from the tool, and means for subsequently increasing the pressure to which the piston is exposed.

2. In a iiuid-pressure-operated tool, the combination with a cylinder, of a differential piston therein the smaller area of which is exposed to a constant pressure toward the tool, means for exposing the larger area of the piston to pressure iiowing from the motive fluid source to impart an initial movement to the piston away from the tool, and means for accelerating said movement of the piston after the motive-fluid source has been cut off.

3. In a fluid-pressure-operated tool, the combination with a cylinder, of' a differential piston therein controlling the admission of fluid-pressure from the motive-duid source to impart an initial movement to the piston away from the tool, and a reservoir the communication of which with the cylinder is controlled by the piston to accelerate the movement of the piston away from the tool.

4E. In a fluid-pressure-operated tool, the combination with a cylinder, of a reciprocating piston in said cylinder, a reservoir adapted to be charged with Huid-pressure, means for admitting pressure from the motive-fluid source to impart an initial movement lo the piston away from the tool, means for cuttingV ting pressure from said reservoir to accelerate the movement of the piston.

5. In a fluid-pressure-operated tool, the combination with a cylinder, of a differential piston exposed to a constant pressure toward the tool, said cylinder having a reservoir formed therein having ports controlled by the piston whereby pressure is first admitted from the motive-duid source to impart an initial movement to the piston away from the tool and subsequently admitted from said reservoir to accelerate the movement of the piston.

6. In a duid-presenre-operated tool, the combination with a cylinder, of a bushing therein said cylinder and bushing being spaced apart to form a reservoir, a differential piston within said bushing exposed to a constant pressure toward the tool and controlling the admission of pressure to said reservoir from the motive-fluid source and also controlling the discharge of said reservoir into said cylinder to accelerate the movement of the piston away from the tool.

7. In a fluid-pressure-operated tool, the combination with a cylinder, of a bushing located within said cylinder so as to form a reservoir between the interior surface of the cylinder and the exterior surface of the bushing, a reciprocating diderential piston within said bushing controlling ports therein through which pressure is admitted to said reservoir and also controlling ports in said bushing through which pressure in said reservoir is discharged into the cylinder to accelerate the movement of the piston away from the tool.

8. In a luid-pressure-operated tool, the combination with a cylinder, of a bushing located within said cylinder so as to form a reservoir between the interior surface of the cylinder and the exterior surface of the bushing, the diameter of the bore of said bushing being less near the end thereof adjacent to the handle of the tool, said bushing having a port through the restricted portion thereof and also a port through the larger portion thereof, a differential piston subjected to a constant pressure toward the tool controlling said ports through the bushing whereby pressure is admitted to said reservoir during the initial movement of the piston away from the tool and discharged from said reservoir into the cylinder after such initial movement of the piston.

9. In a fluid-pressure-operated tool, the combination with a cylinder, of a bushing located withiu said cylinder so as to form a reservoir between the interior surface of the cylinder and the exterior surface of the bushing, the diameter of the bore of said bushing being less near the end thereof adjacent to the handleof the tool, said bushing having a port through the restricted portion thereof, a restricted port through the opposite end thereof, and a relatively larger port therethrough at a predetermined distance from IOO said restricted port, a differential piston withnected from the motive-Huid source and con- 1o in said bushing subjected to aconstant presnected with the cylinder to accelerate the sure toward the tool controlling said ports movement of the piston.

through the bushing whereby said reservoir In testimony whereof I sign this specificais connected to the source of motive-fluid tion in the presence of two witnesses.

supply while pressure is admitted through CHARLES H. JOHNSON. said restricted port t0 impart an initial move- Witnesses:

ment to the piston away from the tool and H. H. VAUGHAN,

whereby subsequently the reservoir is disconi ROY SMITH. 

